Cooling And Heating Degree Days - Cities And FUAs

This dataset provides indicators of Cooling and Heating Degree Days (CDDs and HDDs) for FUAs and cities. CDDs and HDDs are measurements used to estimate energy usage based on outdoor temperature. CDD measures the demand for cooling, while HDD measures the demand for heating, both calculated relative to a baseline temperature.

Data sources and methodology

The indicators use 0.1-degree resolution grids from the ERA5-Land dataset. Annual CDDs are the sum over a year of the differences between the daily mean outdoor air temperature and the threshold temperature when the outdoor temperature is above the threshold temperature. HDDs are the sum over a year of the differences between the threshold temperature and the daily mean outdoor air temperature when the outdoor temperature is below the threshold temperature. Threshold temperatures are set to 22°C for CDDs and 15°C for HDDs.

Defining FUAs and cities

The OECD, in cooperation with the EU, has developed a harmonised definition of functional urban areas (FUAs) to capture the economic and functional reach of cities based on daily commuting patterns (OECD, 2012). FUAs consist of:

1. A city – defined by urban centres in the degree of urbanisation, adapted to the closest local administrative units to define a city.
2. A commuting zone – including all local areas where at least 15% of employed residents work in the city.

The delineation process includes:

• Assigning municipalities surrounded by a single FUA to that FUA.
• Excluding non-contiguous municipalities.

The definition identifies 1 285 FUAs and 1 402 cities in all OECD member countries except Costa Rica and three accession countries.

Cite this dataset

OECD Regions, cities and local areas database (Cooling and heating degree days - Cities and FUAs), http://oe.cd/geostats

Further information

• OECD Local Data Portal
• OECD Regions and Cities at a Glance

For questions and/or comments, please email CitiesStat@oecd.org